This invention is in the field of materials used to prevent the formation of scar tissue subsequent to a surgical procedure or accidental skin cut of a human subject.
Post-operative adhesions are a major problem following abdominal and other surgical procedures. These adhesions are caused by the unwanted proliferation of scar tissue between internal tissues and structures of the human body generally after surgery. Several companies have developed sheets of biodegradable mesh that can be placed between these structures to reduce the tissue growth. None are entirely effective as some scar tissue typically grows through the mesh. U.S. Pat. No. 5,795,286 describes the use of a beta emitting radioisotope to reduce the proliferation of tissue through a biocompatible material placed into the human body. Although radioisotopes may be effective at preventing the cell proliferation associated with adhesions, the limited shelf life and safety issues associated with radioisotopes makes them less than ideal for this purpose.
Recent publications (Transcutaneous Cardiovascular Therapeutics 2000 Abstracts) report a greatly reduced cell proliferation within angioplasty injured arteries when vascular stents used for recannalization are coated with an anti-proliferative drug such as Rapamycin (Sirolmus) or Taxol. However, these drugs have never been used for reducing cellular proliferation of tissues separated by a surgical procedure.
A first embodiment of this invention is a device consisting of a drug impregnated into, coated onto or placed onto a material sheet or mesh designed to be placed between internal body tissues that have been surgically separated to prevent the formation of post-operative adhesions, which adhesions are really scar tissue formation. A drug that is impregnated into a gauze-like material or coated onto the material or joined to the material by adhesion and/or capillary action is defined herein as a drug xe2x80x9cattachedxe2x80x9d to a mesh. This mesh or gauze onto which the drug is attached may be either a permanent implant or it may be biodegradable. The drug can be attached to an existing product such as the Johnson and Johnson SURGICEL(trademark) absorbable hemostat gauze-like sheet. With an anti-proliferative drug such as Rapamycin or Taxol which have a known effect on proliferating cells, the biodegradable mesh would decrease cellular proliferation and hence be a deterrent to the formation of adhesions. It is also envisioned that an anti-proliferative drug attached to a bandage could be placed onto a cut in the skin for reducing scar tissue formation. This cut could be accidental or a result of a surgical incision. It is also envisioned that an anti-proliferative drug could be attached to surgical suture material that is used (for example) to join together two blood generally cylindrical cavitys, i.e., an anastomosis, with the attached drug causing a reduction in cellular proliferation in the vicinity where the sutures penetrate through the human tissue. It should be understood that the suture material could be either soluble or insoluble and could be used for any application for which sutures are used. Still another embodiment of the present invention is an anti-proliferative drug coated onto a surgical staple thus reducing scar tissue around that staple. Still another embodiment of this invention is to attach an anti-proliferative drug to a device such as a buckle that is used for the treatment of a detached retina. Since scar tissue formation is one of the main complications of a retinal attachment procedure, by attaching an anti-proliferative drug to the buckle that is placed around the eye, there can be some reduction in scar tissue formation. It is also envisioned to attach an anti-proliferative drug attached to the outside of a cylindrical tube that is placed within a generally cylindrical cavity of the human body to decrease scar tissue formation after a surgical procedure on that generally cylindrical cavity. Such a generally cylindrical cavity might be a nostril after an operation for a deviated septum, a fallopian tube, a billiary duct, a urethra, (for example after prostate surgery) a ureter, a bronchial tube, etc. For such an application, the tube with the attached anti-proliferative drug could be biodegradable, remain implanted or it could be removed after a few days or weeks.
Another device that would benefit from a coating of an anti-proliferative agent such as Rapamycin is a prosthetic implant that is placed into a woman""s breast after reconstructive or augmentative surgery. Breast implants typically form significant scar tissue around their surface after implantation. Coating the surface of the breast implant with a slowly releasing anti-proliferative agent can significantly reduce this scar tissue formation.
Still another application of these concepts is for aterio-venous fistulas that are used for kidney dialysis patients. These devices (which are also called a-v shunts) are used to connect an artery in an arm to a large vein in the same arm. The plastic a-v shunt is then penetrated by comparatively large needles through which the patient""s blood is cleansed typically every other day. A frequent cause of failure for these shunts is caused by proliferative cell growth at the anastamosis where the shunt is joined to a vein. By having sutures coated with an anti-proliferative agent and by coating the interior and/or exterior of the a-v shunt with an anti-proliferative agent it is expected that the time for maintaining adequate blood flow through the vein will be extended.
In addition to applying the anti-proliferative drug by means of a device to which the anti-proliferative drug is attached, it is also envisioned to apply the anti-proliferative drug systemically by any one or more of the well known means for introducing a drug into a human subject. For example, an anti-proliferative drug could be applied by oral ingestion, by a transdermal patch, by a cream or ointment applied to the skin, by inhalation or by a suppository. Any of these methods being a systemic application of an anti-proliferative drug. It should be understood that such a drug should be applied systemically starting at least one day prior to a surgical procedure but could be started as long as 5 days prior to a surgical procedure. Furthermore, the drug should be applied for a period of at least one day after the procedure and for some cases as long as 60 days. It should be understood that an anti-proliferative drug could be given systemically without using any of the devices described herein. Preferably, the anti-proliferative drug would be given systemically in addition to the application of an anti-proliferative drug attached to any one or more of the devices described herein. It should also be understood that an optimum result might be obtained with using one anti-proliferative drug attached to a device with a second and/or third drug being used for systemic administration. A typical dose for a patient, for example with Rapamycin, would be 1.5 mg/kg per day. The dose would of course depend on the anti-proliferative drug that was used.
Thus it is an object of this invention to have a sheet of material that can be placed between internal body tissues, the material having an anti-proliferative drug attached to reduce scar tissue formation between adjacent layers of the human tissue.
Another object of this invention is to have a biodegradable sheet of material or mesh suitable for placement between body tissues including an attached drug that prevents the cellular proliferation associated with post-surgical adhesions.
Still another object of the invention is to have a bandage to which an anti-proliferative drug is attached that is placed onto a cut in the skin to reduce scar tissue formation.
Still another object of the invention is to have a suture material or surgical staple to which an anti-proliferative drug is attached.
Still another object of the invention is to have an anti-proliferative drug attached to the exterior of a cylindrical tube that is placed into a generally cylindrical cavity of the human body after a surgical procedure on that generally cylindrical cavity.
Still another object of the invention is to have a device implanted in a human subject, the device having an anti-proliferative agent attached; the device being a breast implant, an a-v shunt or an equivalent device for implantation into the human subject.
Still another object of this invention is to have the anti-proliferative drug be Rapamycin or an equivalent drug.
Still another object of this invention is to have the anti-proliferative drug be Taxol or an equivalent drug.
Still another object of the invention is to employ a device placed into or onto the body of a human subject, which device has an attached anti-proliferative drug, plus using the same or a different anti-proliferative drug as a medication to be applied systemically to the human subject from some time prior to a surgical procedure to some time after that procedure.
These and other objects and advantages of this invention will become obvious to a person of ordinary skill in this art upon reading of the detailed description of this invention including the associated drawings.